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Study into how magic mushrooms work in the brain produces surprising results

From the Independent Scientific Committee on Drugs media release,
23 January 2012

The findings of new research into the effects of psilocybin, the psychedelic drug chemical in magic mushrooms, are exciting scientists looking for therapies to treat psychiatric conditions.

Two new studies of this drug’s effect in humans are being published this week. Both contribute fresh knowledge to our understanding of psychedelic effects, which remain among the most mysterious human experiences.

The journal Proceedings of the National Academy of Sciences (PNAS) today publishes the results of a study which used two forms of brain scanning to investigate the effects of a moderate dose of psilocybin on 30 volunteers.

The subjective effects that the volunteers reported included dreamlike distortions of time, space and sensation, visions of geometric patterns, vivid flights of imagination and freely wandering thoughts. The scientists hoped to link these effects to observable changes in the brain.

The two fMRI techniques used measure blood flow and oxygenation. These factors are closely tied to brain activity, so measuring them amounts to an indirect measure of brain activity itself. Psychedelic drugs are popularly described as ‘mind-expanding’, but to the experimenters’ surprise, both forms of brain scan, BOLD fMRI and ASL fMRI, indicated only a reduction in brain activity.

The similarity of the results from the two techniques strongly support the validity of the conclusions, and further testing was carried out to demonstrate that changes observed in the blood oxygenation were due to changes in brain activity and not due to any direct effects of psilocybin on the brain’s blood supply.

When the volunteers were injected with psilocybin, the brain areas richest in connections to other areas quietened down. The posterior cingulate cortex (PCC) and the medial prefrontal cortex (mPFC) are usually amongst the busiest parts of the brain, acting as information hubs, integrating sensory data into higher level thought. As Professor Nutt, the senior author of both papers explained, “this loss of connectivity might mean that consciousness is less constrained by inputs from the outside world via the senses, which could explain why people can imagine things very vividly”.

The team found that the more that activity in the mPFC was reduced by the drug, the more intense the volunteers found the psychedelic experience to be. This is persuasive evidence that the observed effects in the brain were indeed an explanation of subjective effects people feel. Whilst this by no means completes the scientific understanding of the psychedelic experience, for the first time, scientists were able to identify changes in the brain that underpin mental experiences that have been known about for thousands of years.

Previous studies on psilocybin have shown some very promising effects in combating depression, without the need for long-term medication. The suppression of the mPFC that the researchers observed provides an explanation of why. Depressed people have been shown to have greater levels of activity in the mPFC, which is believed to be linked to a tendency to brood persistently on fixed pessimistic thoughts. Upon recovery, the overactivity of the mPFC in depressed individuals has been seen to ebb. The researchers hypothesise that since psilocybin helps reduce mPFC activity, it could be used to break down entrenched negativity. Further research will be able to test these ideas.

The study to be published online later this week by the British Journal of Psychiatry investigated the effects of psilocybin on the recollection of emotionally significant memories. Dr Robin Carhart-Harris, a senior author of both studies, said “psilocybin was used extensively in psychotherapy in the 1950s, but the biological rationale for its use has not been properly investigated until now. Our findings support the idea that psilocybin facilitates access to personal memories and emotions.”

Fifteen volunteers were placed in an MRI scanner, then required to close their eyes and recollect specific personal memories which they had previously listed as having been happy, such as being at the altar getting married. Their brain activity was recorded, and they were also asked to rate aspects of their experience, such as how vivid the memories were. Each volunteer did this twice, once they were injected with psilocybin, and once they were injected with inactive saline (placebo).
The volunteers found that their memories whilst under the influence of psilocybin were significantly more visual and vivid. One participant said that the drug made him feel “more attached to the images and putting myself in the scenario”.

The fMRI imaging of their brains gave an insight into neurological processes behind their vivid recollections. When the participants were given psilocybin, brain regions involved with the senses were activated as they contemplated memories. The memories had a deeper sense of realism as their imaginations seemed to be creating a window into the sights and sounds of their pasts.
Dr Robin Carhart-Harris said “This effect needs to be investigated further but it suggests that used in combination with psychotherapy, psilocybin might help people recall positive life events and reverse pessimistic mindsets.

Psilocybin is a Class A drug under the UK’s Misuse of Drugs Act. According to the hovernment, “Class A drugs are considered to be the most likely to cause harm”, and so possession of them carries the highest penalties; up to seven years in prison and an unlimited fine. The classification of psilocybin under UK law follow the United Nations Convention on Psychotropic Substances, which in 1973 designated psilocybin as Schedule 1, the category with the most stringent controls. However, the law makes a particular exception for research. Professor Nutt holds a rare Home Office licence for the storage and handling of drugs in studies such as these. The risks of administering psilocybin were carefully managed, including by recruiting only volunteers with previous positive experience of psychedelics, and the studies were approved by NHS research ethics committees.

The Schedule 1 classification, which psilocybin received back in 1973, is reserved for drugs which, when listed, were considered not only immensely dangerous, but also of no therapeutic value. Schedule 1 status raises numerous obstacles for research, and in the last four decades these new studies are among the only projects on psilocybin in human subjects that have been able to proceed. The new evidence that has been collected brings into question whether the stringent regulation of Schedule 1 drugs really does serve the interests of public health. More research is urgently needed to fully evaluate the safety and effectiveness of psilocybin as a therapeutic tool, but with so few scientists licensed to carry out this work, this will be a slow process. If psilocybin could indeed be used to relieve the suffering of people with psychiatric disorders, it is unfortunate that sufferers will not have access to this in the coming years.

The research is the product of collaboration of a diverse group of people from across several disciplines and institutions, including the Neuropsychopharmacology Unit at Imperial College London, the Unit of Psychiatry at the University of Bristol, and Cardiff University’s Brain Research Imaging Centre. Professor David Nutt, the Chair of the Independent Scientific Committee on Drugs, was the senior author of both studies. The study in PNAS was edited by Professor Les Iversen of Oxford University, the Chair of the Government’s Advisory Council on the Misuse of Drugs. It was funded by the Beckley Foundation, the Multidisciplinary Association for Psychedelic Studies, and the Heffner Research Institute, all bodies which support the scientific investigation of consciousness and the use of psychedelics to alleviate suffering.

Brain scans of people under the influence of the psilocybin, the active ingredient in magic mushrooms, have given scientists the most detailed picture to date of how psychedelic drugs work. The findings of two studies being published in scientific journals this week identify areas of the brain where activity is suppressed by psilocybin and suggest that it helps people to experience memories more vividly.

In the first study, published today in Proceedings of the National Academy of Sciences (PNAS), 30 healthy volunteers had psilocybin infused into their blood while inside magnetic resonance imaging (MRI) scanners, which measure changes in brain activity. The scans showed that activity decreased in "hub" regions of the brain – areas that are especially well-connected with other areas.

The second study, due to be published online by the British Journal of Psychiatry on Thursday, found that psilocybin enhanced volunteers' recollections of personal memories, which the researchers suggest could make it useful as an adjunct to psychotherapy.

Professor David Nutt, from the Department of Medicine at Imperial College London, the senior author of both studies, said: "Psychedelics are thought of as 'mind-expanding' drugs so it has commonly been assumed that they work by increasing brain activity, but surprisingly, we found that psilocybin actually caused activity to decrease in areas that have the densest connections with other areas. These hubs constrain our experience of the world and keep it orderly. We now know that deactivating these regions leads to a state in which the world is experienced as strange."

The intensity of the effects reported by the participants, including visions of geometric patterns, unusual bodily sensations and altered sense of space and time, correlated with a decrease in oxygenation and blood flow in certain parts of the brain.

The function of these areas, the medial prefrontal cortex (mPFC) and the posterior cingulate cortex (PCC), is the subject of debate among neuroscientists, but the PCC is proposed to have a role in consciousness and self-identity. The mPFC is known to be hyperactive in depression, so psilocybin's action on this area could be responsible for some antidepressant effects that have been reported. Similarly, psilocybin reduced blood flow in the hypothalamus, where blood flow is increased during cluster headaches, perhaps explaining why some sufferers have said symptoms improved under psilocybin.

In the British Journal of Psychiatry study 10 volunteers viewed written cues that prompted them to think about memories associated with strong positive emotions while inside the brain scanner. The participants rated their recollections as being more vivid after taking psilocybin compared with a placebo, and with psilocybin there was increased activity in areas of the brain that process vision and other sensory information.

Participants were also asked to rate changes in their emotional wellbeing two weeks after taking the psilocybin and placebo. Their ratings of memory vividness under the drug showed a significant positive correlation with their wellbeing two weeks afterwards. In a previous study of 12 people in 2011, researchers found that people with anxiety who were given a single psilocybin treatment had decreased depression scores six months later.

Dr Robin Carhart-Harris, from the Department of Medicine at Imperial College London, the first author of both papers, said: "Psilocybin was used extensively in psychotherapy in the 1950s, but the biological rationale for its use has not been properly investigated until now. Our findings support the idea that psilocybin facilitates access to personal memories and emotions.

"Previous studies have suggested that psilocybin can improve people's sense of emotional wellbeing and even reduce depression in people with anxiety. This is consistent with our finding that psilocybin decreases mPFC activity, as many effective depression treatments do. The effects need to be investigated further, and ours was only a small study, but we are interested in exploring psilocybin's potential as a therapeutic tool."

The researchers acknowledged that because the participants in this study had volunteered after having previous experience of psychedelics, they may have held prior assumptions about the drugs which could have contributed to the positive memory rating and the reports of improved wellbeing in the follow-up.

Functional MRI measures brain activity indirectly by mapping blood flow or the oxygen levels in the blood. When an area becomes more active, it uses more glucose, but generates energy in rapid chemical reactions that do not use oxygen. Consequently, blood flow increases but oxygen consumption does not, resulting in a higher concentration of oxygen in blood in the local veins.

In the PNAS study, the volunteers were split into two groups, each studied using a different type of fMRI: 15 were scanned using arterial spin labelling (ASL) perfusion fMRI, which measures blood flow, and 15 using blood-oxygen level-dependent (BOLD) fMRI. The two modalities produced similar results, strongly suggesting that the observed effects were genuine.

More information: R Carhart-Harris et al. 'Neural correlates of the psychedelic state as determined by fMRI studies with psilocybin.' Proceedings of the National Academy of Sciences, published online 23 January 2012.
R Carhart-Harris et al. 'Implications for psychedelic-assisted psychotherapy: a functional magnetic resonance imaging study.' British Journal of Psychiatry, published online 26 January 2012.

Re: Study into how magic mushrooms work in the brain produces surprising results

All I can sy is I really do miss the days when I had the privilege of enjoying and personally I will say benefiting from psilocybin ....

Everyone is different so do your homework, but it did do positive wonders for me, and for a small group of friends that will still agree today, some 20years later.I never suffered from any Psychiatric issues however will stick to my statement.

Be safe. Do your research and ask the questions before trying any drug.

However, he said they were not being studied because of the restrictions placed on researching illegal drugs.

He said the regulations were "overwhelming".

His comments followed the publication of new research by his group in the Proceedings of the National Academy of Sciences, which suggests that the active ingredient in magic mushrooms could be used to treat depression.

"I feel quite passionately that these drugs are profound drugs; they change the brain in a way that no other drugs do. And I find it bizarre that no-one has studied them before and they haven't because it's hard and illegal," he said.

A Home Office spokesperson said: "The Home Office licensing regime already enables research to take place through a system of controlled drug possession licences, allowing bona fide institutions to carry out scientific research.

"This regime recognises the importance of such research and enables that to take place in an appropriate environment, ensuring the necessary safeguards are in place."

Fired

Prof Nutt was sacked by the home secretary from his government advisory role three years ago for saying that ecstasy and LSD were less harmful than alcohol.

He says his new research indicated that there were no "untoward effects" from taking magic mushrooms and that it should not be illegal to possess them.

Prof Nutt and his team scanned the brains of volunteers who had been injected with a moderate dose of psilocybin, the active ingredient of magic mushrooms.

They had expected higher activity in areas of the brain associated with visual imagery. But in fact they found that the drug switched off a network of interconnected regions of the brain which regulated an individual's sense of being and integration with their environment.

The researchers say that this alters consciousness because individuals are less in touch with their sensations and normal way of thinking.

Medical role?

They also found that psilocybin also turns off a part of the brain which is overactive in some forms of depression. So Prof Nutt believes that the drug could be used as an antidepressant and has applied to the Medical Research Council to carry out a small patient study to see if this is the case.

"There's some research from the US which shows that when used in a psycho-therapeutic context it can produce quite long-lasting changes to a person's sense of well-being - changes that can last for years," he says.

He also said that there was nothing in the brain scans or follow-up studies which would suggest that if taken in moderate quantities the drug was unsafe.

"People who use them regularly seem to do that. They seem to use them on an annual basis in order to enjoy the experience but also because it has this positive reaffirming effect.

"And there are certainly examples of people who take magic mushroom tea for obsessive compulsive disorder to keep it under control.

"So it may be that there are broad utilities of these kind of compounds in terms of mental well-being. I don't know - I think it's very much a question to be answered."

A second study, due to be published online by the British Journal of Psychiatry on Thursday, found that psilocybin enhanced volunteers' recollections of personal memories, which the researchers suggest could make it useful as an adjunct to psychotherapy.

However, Martin Barnes, chief executive of DrugScope, said: "The research published today does not directly address whether or not magic mushrooms are harmful.
"Instead, it looks at how psilocybin, the active chemical in magic mushrooms, affects the brain."

Prof Nutt also said that he believed that possession of magic mushrooms should not be illegal, adding that its status as a controlled drug was hampering research.
"Research has been minimal, if not non-existent, on psychedelic drugs because the regulations are so overwhelming," he said.

"I would say that this is the most obvious unexplored area of neuroscience; drugs which change the brain in a fundamental way and yet we don't bother studying them because it's too difficult or we are to scared of falling foul of the regulators or the media."

But Mr Barnes from DrugScope cautioned that the recreational or problematic use of drugs should not be conflated with the important issue of researching possible therapeutic or medical benefits that some psychoactive substances may offer.

"A carefully controlled and supervised study, using a pure formulation of psilocybin under controlled conditions, is very different from how most people would ingest the substance in magic mushrooms. As with medicines which use active chemicals present in cannabis, pharmaceutical products derived from any psychoactive substances will differ significantly from street drugs."

Prof Nutt resists comparisons with the 1960s guru Timothy Leary who advocated the use of LSD. His view was that if everyone took LSD all the time they would be better people. They would have nicer, happier lives.

"I'm not recommending anyone taking any drugs. I'm just suggesting we need to have a more scientific rational approach to drugs and vilifying drugs like psilocybin whilst at the same time actively promoting much more dangerous drugs like alcohol is totally stupid scientifically."

A new brain-scan study helps explain how psilocybin works — and why it holds promise as a treatment for depression, addiction and post-traumatic stress.

By Maia Szalavitz
More than half a century ago, author Aldous Huxley titled his book on his experience with hallucinogensThe Doors of Perception, borrowing a phrase from a 1790 William Blake poem (which, yes, also lent Jim Morrison’s band its moniker). Blake wrote:

If the doors of perception were cleansed, every thing would appear to man as it is, infinite. For man has closed himself up, till he sees all things through narrow chinks of his cavern.

Based on this idea, Huxley posited that ordinary consciousness represents only a fraction of what the mind can take in. In order to keep us focused on survival, Huxley claimed, the brain must act as a “reducing valve” on the flood of potentially overwhelming sights, sounds and sensations. What remains, Huxley wrote, is a “measly trickle of the kind of consciousness” necessary to “help us to stay alive.”

A new study by British researchers supports this theory. It shows for the first time how psilocybin — the drug contained in magic mushrooms — affects the connectivity of the brain. Researchers found that the psychedelic chemical, which is known to trigger feelings of oneness with the universe and a trippy hyperconsciousness, does not work by ramping up the brain’s activity as they’d expected. Instead, it reduces it.

Under the influence of mushrooms, overall brain activity drops, particularly in certain regions that are densely connected to sensory areas of the brain. When functioning normally, these connective “hubs” appear to help constrain the way we see, hear and experience the world, grounding us in reality. They are also the key nodes of a brain network linked to self-consciousness and depression. Psilocybin cuts activity in these nodes and severs their connection to other brain areas, allowing the senses to run free.

“The results seem to imply that a lot of brain activity is actually dedicated to keeping the world very stable and ordinary and familiar and unsurprising,” says Robin Carhart-Harris, a postdoctoral student at Imperial College London and lead author of the study published in Proceedings of the National Academy of Sciences.

Indeed, Huxley and Blake had predicted what turns out to be a key finding of modern neuroscience: many of the human brain’s highest achievements involve preventing actions instead of initiating them, and sifting out useless information rather than collecting and presenting it for conscious consideration.

For the study, the authors recruited 15 brave volunteers to receive injections of psilocybin or placebo, in alternate sessions, while being scanned in an fMRI machine. Taken intravenously, psilocybin alters consciousness in a mere 60 seconds, as opposed to the 40 minutes it normally takes when administered orally. And the high lasts a half an hour, not the five hours that typical users experience.

Provisions were made for the possibility that the participants might panic while high in the noisy, claustrophic setting of the scanner, but none of the volunteers did so. In fact, once they’d become accustomed to the noise and small space, “they quite liked being enclosed and felt secure,” Carhart-Harris says. All of the participants had previously been, as Jimi Hendrix put it, “experienced.”

Researchers had assumed that the hallucinations and bizarre sensations caused by psilocybin would have at least one part of the brain working overtime. But instead they found the opposite.

“The decline in activity was the most surprising finding,” says Carhart-Harris, “and anything that’s of surprise is usually important.”

Reducing the brain’s activity interfered with its normal ability to filter out stimuli, allowing participants to see afresh what would ordinarily have been dismissed as irrelevant or as background noise. They described having wandering thoughts, dreamlike perceptions, geometric visual hallucinations and other unusual changes in their sensory experiences, like sounds triggering visual images.

Indeed, if we always paid attention to every perceptible sensation or impulse like this, we’d be incapable of focusing at all. This is why it’s difficult to sit still and try to tune in all the feelings and perceptions we normally tune out, but why also, like psychedelic drugs, meditation can make the world seem strange and new.

The particular brain regions that were silenced or disconnected from each other by the drug also provided insight on the nature of psychedelic experience and the therapeutic potential of psilocybin. Two regions that showed the greatest decline in activity were the medial prefrontal cortex (mPFC) and the posterior cingulate cortex (PCC).

The mPFC is an area that, when dysfunctional, is linked with rumination and obsessive thinking. “Probably the most reliable finding in depression is that the mPFC is overactive,” says Carhart-Harris.

All antidepressant treatments studied so far — from Prozac, ketamine, electroconvulsive therapy and talk therapy to placebo — reduce activity in the mPFC when they are effective. Since psilocybin does the same, Carhart-Harris and his colleagues plan to study it as a treatment for depression. “It shuts off this ruminating area and allows the mind to work more freely,” he says. “That’s a strong indication of the potential of psilocybin as a treatment for depression.”

The PCC is thought to play a key role in consciousness and self-identity. “The most intriguing aspect was that the decreases in activity were in specific regions that belong to a network in the brain known as the default network,” notes Carhart-Harris. “There’s a lot of evidence that it’s associated with our sense of self — our ego or personality, who we are.”

“What’s often said about psychedelic experience is that people experience a temporary dissolution of their ego or sense of being an independent agent with a particular personality,” he says. “Something seems to happen where the sense of self dissolves, and that overlaps with ideas in Eastern philosophy and Buddhism.” This sense of being at one with the universe, losing one’s “selfish” sense and vantage point, and feeling the connectedness of all beings often brings profound peace.

The researchers also looked for an effect on the language-processing areas of the brain, since users so often report that their experience is difficult to put into words. “There wasn’t any correlation between people saying that the experience was ineffable and any change in brain activity,” Carhart-Harris says. “It may just be because the way we symbolize the world with language is a constrained function. It has a degree of precision to it, really, and these drug experiences are so unusual we don’t have words to describe them.”

Carhart-Harris and his colleagues did find support for claims made by sufferers of painful cluster headaches that psilocybin reduces the frequency of their attacks. These headaches are known to involve overactivity of a brain area called the hypothalamus, and psilocybin calmed this region.

Interestingly, Nature‘s Mo Costandi reports that another study of the effects of psilocybin on the brain found the opposite effect of Carhart-Harris’ group:

“We have completed a number of similar studies and we always saw an activation of these same areas,” says Franz Vollenweider at the University of Zurich in Switzerland. “We gave the drug orally and waited an hour, but they administered it intravenously just before the scans, so one explanation is that [their] effects were not that strong.”*

Another neuroscientist told Nature that some studies find that lowered activation of the mPFC is associated with anticipatory anxiety rather than calmness or overall lack of depression. The researcher theorizes that the brain images in the current study picked up the participants’ fear, rather than their mystical experiences. But that conflicts with participants’ reports: they said their trips were mainly positive.

Carhart-Harris cautions against using psilocybin outside of a well-monitored therapeutic setting, however, particularly for patients with depression. “What we found was in healthy volunteers,” he says. “They liked the experience and didn’t have negative reactions, but during depression people are more sensitive to having a negative response to psychedelic drugs.”

In fact, that may help explain why psychedelic drugs are rarely addictive and why some of them may even have potential to treat other addictions. Unlike addictive drugs, which typically allow users to escape, psychedelic drugs have the opposite effect: instead of allowing users to avoid negative emotions, they magnify the painful feelings. Researchers believe this may help patients address their problems instead of fleeing them — in the context of an empathetic therapeutic setting — but it can also exacerbate distress. (Psilocybin is illegal in the U.S. and is considered a Schedule 1 drug, a class of substances that “have a high potential for abuse and serve no legitimate medical purpose in the United States,” according to the Department of Justice. Other Schedule 1 drugs include marijuana, heroin and LSD.)

Indeed, the new research bolsters the idea of “psychedelic” as an accurate label for these drugs. The word was originally coined by Huxley, from the Greek “psyche” for mind or soul and “delos” for manifest. A growing body of literature suggests that these drugs can indeed help scientists understand the workings of the mind and brain, by revealing some of the underpinnings of consciousness.

Some have argued, for example, that the geometric visual hallucinations commonly seen by people on psychedelics (and by some sufferers of migraines) help reveal the architecture of the brain’s visual processing mechanism. “One hypothesis is that what you’re actually seeing is the functional organization of the visual cortex itself. The visual cortex is organized in a sort of fractal way [it repeats the same patterns in different sizes]. It’s the same way that fractals are everywhere in nature. Like tree branches, the brain recapitulates [itself],” says Carhart-Harris. “You’re not seeing the cells themselves, but the way they’re organized — as if the brain is revealing itself to itself.”

Magic mushrooms are said to blow your mind, but the hallucinogenic chemical psilocybin, the active ingredient, actually reins in key parts of the brain, according to two new studies.

The memorably vivid emotional experiences reported by mushroom users may flourish because the parts of the brain suppressed by psilocybin usually keep our world view tidy and rational.

And since the brain area affected by psilocybin can also be out of whack in mental health problems such as depression, the researchers speculate that the drug may turn out to be useful in treating mental illness.

"The brain's doing a lot to keep our experiences of the world orderly and constrained," says Robin Carhart-Harris, a post-doc in neuroscience at Imperial College London, and lead author of the studies.

The studies are among the first to use brain imaging to take a peek at the brain on psilocybin.
"Depression can be described as a particularly restrictive state of mind," Carhart-Harris told Shots. "People are stuck on how terrible they are. This seems to suggest that people can have a lifting of that negative thinking under psychedelics."

One of the studies asked 10 volunteers to recall particularly happy memories, like getting married or becoming a parent, both with and without psilocybin. The people found the memories much more vivid, visual, and happy while under the influence. That study will be published in the British Journal of Psychiatry on Thursday.

In the second study, 30 volunteers lay in an MRI machine while tripping for science. The brain scans showed less activity in areas of the brain that may act as connectors, or hubs. One of those areas, the posterior cingulate cortex, is thought to figure in consciousness and ego. It's also hyperactive in people with depression.

The researchers hadn't expected to find less brain activity with psilocybin. The thought has always been that psychedelic flights of fancy are the result of an overactive brain. The results were published Monday in the Proceedings of the National Academy of Sciences.

Serious research into psychedelic drugs was pretty much shut down after the excesses of the trip-happy 1960s. Harvard famously fired Timothy Leary in 1963 for experimenting far too enthusiastically with psilocybin and other mind-altering drugs. Psilocybin remains an illegal drug in the same category as heroin and LSD, which the Justice Department says has "no legitimate medical purpose."

Still, several recent small studies have found improvements in people with depression or obsessive-compulsive disorder after taking other psychedelics. Another found less anxiety and improved mood in cancer patients who used psilocybin.

Carhart-Harris says he was inspired to experiment with psilocybin by Roland Griffiths, a neuroscientist at Johns Hopkins University in Baltimore. Last year Griffiths reported that when he tested high doses of psilocybin in 18 volunteers, 72 percent reported profoundly spiritual experiences, as well as improvements in mood and attitude that lasted more than a year.

But those trips weren't all good; 39 percent reported extreme anxiety or fear at some point in the five 8-hour sessions. People trained as monitors kept the study participants company in an effort to reduce the impact of those bad experiences.

The next step is to see if psilocybin actually does alleviate symptoms of depression. Carhart-Harris hopes to start a pilot study asking that question by the end of the year.

Last edited by Terrapinzflyer; 25-01-2012 at 02:42.
Reason: paragraph breaks

Rave-goers and visitors to Amsterdam before December 2008 may be intimately familiar with magic mushrooms, but there's little scientific knowledge on what happens to the brain while tripping.

Now it appears that more research is warranted. A growing number of studies suggested that perhaps the mushrooms' key ingredient could work magic for certain mental disorders.

New research in Proceedings of the National Academy of Sciences sheds light on why one of the mushrooms' hallucinogenic chemical compounds, psilocybin, may hold promise for the treatment of depression. Scientists explored the effect of psilocybin on the brain, documenting the neural basis behind the altered state of consciousness that people have reported after using magic mushrooms.

"We have found that these drugs turn off the parts of the brain that integrate sensations – seeing, hearing, feeling – with thinking," said David Nutt, co-author of the study and researcher at Imperial College London in the United Kingdom.

Nutt is also Britain's former chief drug adviser, who has published controversial papers about the relative harms of various drugs. He was asked to leave his government position in 2009 because "he cannot be both a government adviser and a campaigner against government policy," according to a letter in the Guardian from a member of the British Parliament.

Psilocybin is illegal in the United States and considered a Schedule 1 drug, along with heroin and LSD. Schedule 1 drugs "have a high potential for abuse and serve no legitimate medical purpose in the United States," according to the Department of Justice.

But in the early stages of research on psilocybin, there's been a bunch of good news for its medicinal potential: psilocybin has shown to be helpful for terminally ill cancer patients dealing with anxiety, and preliminary studies on depression are also promising.

Nutt's study is also preliminary and small, with only 30 participants. His group used magnetic resonance imaging (MRI) to look at how the brain responds to psilocybin, from normal waking consciousness to a psychedelic state.

The study found that the more psilocybin shuts off the brain, the greater the feeling of being in an altered state of consciousness, he said. It's not the same as dreaming, because you're fully conscious and aware, he said.

The medial prefrontal cortex, the front part of the brain in the middle, appears to be crucial - it determines how you think, feel and behave. Damage to it produces profound changes in personality, and so if you switch it off, your sense of self becomes fragmented, Nutt said. That's what happens when psilocybin decreases activity in it.

"Some people say they become one with the universe," he said. "It's that sort of transcendental experience."

Another brain region that psilocybin affects is the anterior cingulate cortex, which is over-active in depression, Nutt said. Some patients with severe depression that cannot be treated with pharmaceuticals receive deep brain stimulation, a technique of surgically implanting a device that delivers electrical impulses directed at decreasing activity in that brain region. Psilocybin could be a cheaper option, Nutt said.

It's counterintuitive that a hallucinogenic drug would de-activate rather than stimulate key brain regions, although other studies have shown a mix of results regarding psilocybin turning brain areas on and off, said Roland Griffiths, a professor of psychiatry and neuroscience at the Johns Hopkins University School of Medicine. Griffiths was not involved in Nutt's study, but has also researched the effects of psilocybin.

Even if this drug gets approved some day, don't expect to be able to pick up a prescription for psilocybin at your local pharmacy, Griffiths cautioned. There's too much potential for abuse, he said.

Although scientists have found many positive effects of psilocybin in experimental trials, there are of course potential dangers. Some people have frightening experiences while on psilocybin. The fear and anxiety responses of magic mushrooms can be so great that, when taken casually in a non-medical setting, people can cause harm to themselves or others. They may jump out a window or run into traffic because of a panic reaction.

The drug would have to be administered in a controlled setting in a hospital, if found in further research to be an effective and safe therapy for certain mental illnesses, Griffiths said. It would not be appropriate for people who already have psychotic disorders such as schizophrenia, since psilocybin can exacerbate those symptoms.

But among healthy volunteers, Griffiths and others have found that people may have long-lasting positive effects from the vivid memories of being on psilocybin (in a controlled, experimental setting). People report mystical experiences of feeling the "interconnectedness of all things," which can be life-changing.

"People claim to have an enhanced sense of self, more emotional balance, they're more compassionate, they're more sensitive to the needs of others," he said. "They have more well-being and less depression, but they're not 'high' in any conventional sense. They feel like their perceptual set has shifted."

The memories of the psilocybin experience, and positive outcomes that users attribute toward them, can last as much as 25 years, research has shown.

Still, there's just not enough known yet about the long-term safety of psilocybin to say whether it could also do damage to the brain, Griffiths said.

"There’d have to be changes in the brain for these long-lasting memories and attributions to occur," Griffiths said. "We don’t know how those changes occur, and why."